Research Papers in Physics and Astronomy

 

Date of this Version

November 2007

Comments

Published in Journal of Physics: Condensed Matter 19 (2007) 310301 (2 pp); doi:10.1088/0953-8984/19/31/310301 http://www.iop.org/EJ/toc/0953-8984/19/31 Special issue on Half Metallic Ferromagnets Copyright © 2007 Institute of Physics Publishing. Used by permission.

Abstract

Since its introduction by de Groot and colleagues in the early 1980s [1], the concept of half metallic ferromagnetism has attracted great interest. Idealized, half-metals have only one spin channel for conduction: the spin-polarized band structure exhibits metallic behavior for one spin channel, while the other spin band structure exhibits a gap at the Fermi level. Due to the gap for one spin direction, the density of states at the Fermi level has, theoretically, 100 % spin polarization. This gap in the density of states in one spin at the Fermi level, for example ↓ so N↓(EF) = 0, also causes the resistance of that channel to go to infinity. At zero or low temperatures, the nonquasiparticle density of states (electron correlation effects), magnons and spin disorder reduce the polarization from the idealized 100 % polarization. At higher temperatures magnon-phonon coupling and irreversible compositional changes affect polarization further. Strategies for assessing and reducing the effects of finite temperatures on the polarization are now gaining attention.

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